About how many bases (DNA letters) make up human DNA?
Answerabout 3 billion bases
The bases A, T, C and G pair up — A with T, C with G — to form base pairs.
Source: MedlinePlus Genetics, U.S. National Library of Medicine (2024) medlineplus.gov
Science · Facts & sources
Genetic facts & stats
5 sourced facts about genetics and the human genome, each with the context behind the number. 4 more are in today's round and appear here after it closes.
The basics
In what year did scientists announce the first truly complete, gap-free human genome sequence?
AnswerMarch 31, 2022
The Telomere-to-Telomere (T2T) consortium filled in the gaps left by the original Human Genome Project.
Source: National Human Genome Research Institute (2022) genome.gov
Going deeper
The Human Genome Project launched in October 1990. When was it completed?
AnswerApril 2003
Researchers from 20 universities and research centers in the U.S., U.K., France, Germany, Japan and China took part.
Source: National Human Genome Research Institute (2022) genome.gov
Expert level
What share of the human genome did the 'essentially complete' 2003 sequence actually cover?
Answer92%
It still had fewer than 400 gaps. The June 2000 draft covered 90% but had more than 150,000 unknown stretches.
Source: National Human Genome Research Institute (2022) genome.gov
By late 2015, what did it cost to generate a high-quality draft human genome sequence?
Answerbelow $1,500
As recently as 2006 the same kind of sequence cost about $14 million; the U.S. share of the original project was about $2.7 billion.
Source: National Human Genome Research Institute, The Cost of Sequencing a Human Genome (2021) genome.gov
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